The invention relates to a sample handling apparatus designed at least for taking specimens or samples from reaction vessels and for providing a backfeed to the reaction vessels of the same amount of replenishing liquid as the amount (volume) of specimen taken.
Such sample collecting apparatuses are used in the pharmaceutical industry for taking samples or solutions of pharmaceutical products the long-term behaviour of which at body temperature (37.degree. C.) is to be measured. When carrying out such measurements it is important that one measurement is not influenced by the preceding measurement, i.e. that the lines through which the samples to be measured flow have to be cleaned between the individual operations of taking samples. Furthermore, it has to be guaranteed that exactly the same amount of replenishing liquid is fed back to the reaction vessels, as has been taken for a previous sample. For this purpose in previous sample collecting apparatuses replenishing liquid is fed to the reaction vessels through the same pump which also is used for taking the samples. For introducing the replenishing liquid into the pump circulation it is necessary to provide a valve to realize the lines through which the samples flow from the reaction vessels to the test tubes and the line work through which the replenishing liquid flows from the storage vessel to the reaction vessels. The previous sample collecting apparatus has the disadvantage that the lines for the samples are not entirely rinsed by the replenishing liquid, because the lines for the replenishing liquid from the storage vessel to the valve are separate from the lines from the valve to the test tubes. Between the valves and the reaction vessels the liquid samples pass through the same lines as the replenishing liquid, of course the two liquids flowing in opposite directions.